This invention pertains to the field of weapons, and more particularly to cannon chamber propellant gases sealing systems.
Since the introduction of breech loaded weapons requiring the use of separate loaded ammunition, obturation difficulties have been experienced because of the broad range of environmental conditions encounted by said weapons. The obturation system in general use by the U.S. Army is the DeBange system invented in 1876. It is used in all bag loaded artillary, and with minor deviations is basically the same as when invented.
Weapons using bag-loaded ammunition must be provided at the breech with a sealing means that will prevent propellant gases from passing to the rear into the threads or other parts of the breech mechanism. Should leakage paths exist, gases will be forced through said path openings at great velocity due to high chamber pressure. Said gas velocity along with high temperature gives the gases great erosive power such that threads and other parts of the breech mechanism, along with the gas check seat, can be ruined.
Presently used obturator systems utilize a non-metallic elastic pad in conjunction with annular steel split rings to protect the front and rear edges of said pad from being burned by the propellant gases. Said obturation systems do not perform satisfactory under the required operating ambient temperature range. At low temperatures, the elastic sealing pads shrink excessively when compared to the surrounding metal to cause leakage. At high temperatures, said elastic pads expand such as to cause hard closing of the breech. Further problems encounted relate to the relatively short useful life of both pads and steel split rings, and the high cost of manufacture.